Most tissues, such as muscle, skin, and liver, have the ability to repair and regrow after an injury. However, the brain, spinal cord and other nervous system tissues are very limited in their ability to repair and regrow. Neurons, which comprise nervous system tissue, become assembled into functional networks by growing out axons and dendrites, collectively called neurites. They connect synaptically to other neurons, and are critical for communication between each other. Understanding neurite outgrowth is important to nervous system research, because compounds that promote neurite outgrowth have potential curative effects in nervous systems disorders such as stroke, Alzheimer's disease, Parkinson's disease and spinal cord injury.